^aDepartment of Pharmacology, China Pharmaceutical University, Nanjing, 210009, PR China

^bDepartment of Diving Medicine, Faculty of Naval Medicine, Secondary Military Medical University, Shanghai, 200433, PR China

^cDepartment of Neurosurgery, Loma Linda University, Loma Linda, California, USA

Abstract

Hyperbaric oxygen preconditioning (HBO-PC) increases the level of HIF-1α (hypoxia inducible factor-1α) and its target gene VEGF (vascular endothelial growth factor) which is involved in angiogenesis. Liver regeneration is an angiogenesis-dependent process. We hypothesized that HIF-1α and VEGF mediated the angiogenesis effect of HBO-PC on regenerating rat liver. Male Sprague Dawley rats received HBO-PC followed by 70% partial hepatectomy. Proliferation of hepatocytes and endothelial cells was evaluated by BrdU (bromodeoxyuridine) staining. Microvascular density was assessed by immunohistochemistry. mRNA expression of HIF-1α was assessed by quantitative RT-PCR and protein levels of HIF-1α and VEGF were assessed by western blot. HIF-1α DNA-binding activity was determined with an ELISA-based kit. HBO-PC increased the proliferation index of endothelial cells and microvascular density at 48 h after partial hepatectomy. The protein level and DNA-binding activity of HIF-1α and the protein level of VEGF were increased by HBO-PC before and after partial hepatectomy. Partial hepatectomy alone also increased proliferation index and the expressions of HIF-1α and VEGF. Our results indicated that the angiogenesis effect of HBO-PC on liver after partial hepatectomy could be achieved by increased HIF-1α activity and VEGF expression. However, the angiogenic effect of HBO-PC is moderate and HBO-PC failed to produce additional effect on the enhancement of HIF-1α and VEGF induced by partial hepatectomy alone.

Keywords: Angiogenesis; Hyperbaric oxygen preconditioning; Hypoxia inducible factor-1; Vascular endothelial growth factor

Article Outline

Introduction

Materials and methods

Animals and study protocols

Liver regeneration

HBO exposure

Immunohistochemistry

Western blot analysis

HIF-1α DNA-binding assay

RNA isolation and quantitative real-time PCR

Data analysis

Results

Wet regeneration

Proliferation index BrdU

Microvascular density

HIF-1α

VEGF

Discussion

Acknowledgements

References